Method of manufacturing a copper bar induction rotor

Abstract

An improved method of manufacture of a shorted turn copper bar rotor which is amenable to high volume production and which provides a copper-to-copper electrical bond among the conductor bar end turn portions at each end of the rotor core. Once the rotor core laminations have been assembled on the rotor shaft, and the conductor bars have been inserted into the core slots, a cylinder or spool element is positioned in abutment with each axial end of the core to define annular cavities into which the conductor bar end turn portions extend. Each cavity has a continuous opening for permitting access to the end turn portions lying therein, and a molten copper plasma is sprayed into the opening of each cavity, thereby forming a copper-to-copper electrical bond among the end turn portions extending from each end of the core. The ends of the assembly are then shortened as necessary by machining to provide the required current carrying capacity.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A method of manufacture of a shorted turn motor rotor having a ferromagnetic core secured on a rotor shaft, the core having axially extending slots in which are received elongate copper conductor bars, the conductor bars having end turn portions which extend out of the respective slots at each axial end of the core, the method comprising the steps of: positioning a cylindrical element in abutment with each axial end of said core to define at each such end an annular cavity into which said end turn portions of said conductor bars extends, each cavity having a continuous opening in the radial direction for permitting access to end turn portions disposed therein; and   spraying molten copper plasma into each cavity via the respective continuous opening, thereby to form a copper-to-copper electrical bond among the conductor bar end turn portions extending from each end of said core.   
     
     
       2. The method of manufacture set forth in claim 1, wherein said cylindrical elements each comprise coupled inboard and outboard sidewalls, said inboard sidewall being positioned in abutment with a respective axial end of said core, and slotted to receive respective end turn portions of said conductor bars. 
     
     
       3. The method of manufacture set forth in claim 1, including the step of: rotating said core and cylindrical elements while the molten copper plasma is sprayed into said cavities.   
     
     
       4. The method of manufacture set forth in claim 1, where the cylindrical elements are formed in aluminum.